Republican senator Everett Dirksen once coined the phrase "a billion here, a billion there, and pretty soon, it all adds up to real money". Given the amount of money, not to mention time, already invested in getting ready for the EU's revised Markets in Financial Instruments Directive, investment banks could be forgiven for expecting savings to be made from day one.

It is easy to see why. After all, brokers should be acting in the best interests of their clients on every single trade, so banks should always be able...